Spinnerette with head filter

ABSTRACT

The central cavity of a spinnerette head assembly for the extrusion of synthetic polymer fibers is substantially filled by a filter element having a filter disk and upstanding concentric rings extending upward from the disk within the central cavity, the filter area presented to inflowing plastic being at least twice the cross-sectional area of the cavity and the concentric rings occupying at least 45 per cent of the volume of the cavity, the filter element containing concentric circles of closely spaced upward outflow bores extending through the filter disk to the upper portions of the concentric rings.

United States Patent 1 Mott [451 Apr. 24, 1973 [54] SPINNERETTE WITHHEAD FILTER 2,925,913 2/1960 Wheeler "210/ 323 Inventor: Lambert H.Mott, Mott Meta] 3,524,548 8/1970 McDonald et a1. ..210/323X lurglclCorp" Drawer Primary Examiner.l. Spencer Overholser FarmingtonIndustrial Park, E h, 10 S u Farmington Conn. 06032 .mrstant xammer I 10ae u on Attorney-Peter L. Fuller [22] Filed: June 24,1971 [21] App1.No.:156,424 [57] ABSTRACT The central cavity of a spinnerette head assemblyfor the extrusion of synthetic polymer fibers is substan- [52] US. Cl...425/l98, 210/315, 219/338 tiany filled by a filter element having afilter disk and [51] InLCl. ..D0ld3/O0,D2913/00 upstanding concentricrings extending upward from [58] Field of Search ..425/197199; the diskwithin h central cavity, the filter area 210/314 presented to inflowingplastic being at least twice the 496 cross-sectional area of the cavityand the concentric rings occupying at least 45 per cent of the volume of[56] Reference? C'ted the cavity, the filter element containingconcentric cir- UNITED STATES PATENTS cles of closely spaced upwardoutflow bores extending through the filter disk to the upper portions ofthe 3,570,059 3/1971 MOII ..425/198 X ncentric ring5 2,042,564 6/1936Sweetland. ..210/448 X 1,218,738 3/1917 Zahm ..210/323 X 4 Claims, 6Drawing Figures Patented April 24, 1973 2 Sheets-Sheet 1 mwn INVENTORZLAMBERT H. MOTT BY OULXM ATTORNEY.

Patented April 24, 1973 3,729,279

' 2 Sheets-Sheet 2 anyli i jfgo 45 I 4! I" v/./

45 v I 5 $1 5' 4' I D INVEN I LAMBERT H. M

BY 6 d; X 72% ATTORNEY.

BACKGROUND OF THE INVENTION A conventional spinnerette head assembly forthe extrusion of synthetic polymer fibers contains a large centralcavity into which plastic material is forced at extrusion pressures. Aspinnerette disk is fixed to the spinnerette head assembly and containssmall extrusion orifices through which individual fiber strands areextruded. A porous filter is usually placed in the cavity in front ofthe the spinnerette disk to filter foreign particles from the plasticand prevent clogging of the extrusion apertures. The porous filter alsoserves to condition the plastic for extrusion as it shears lumps orinconsistencies in the plastic passing through it. In many cases marblesor sandare. placed in the cavity behind the conventional flat filter toreduce the effective volume of the cavity and prevent the stagnation anddegredation of plastic therein. This invention provides a superiorspinnerette head assembly filter.

SUMMARY OF THE INVENTION A spinnerette head assembly for the extrusionof synthetic polymer fibers has a cup shaped holder containing a centralcavity, a bottom wall of said holder containing passages, a spinnerettedisk contining extrusion orifices fixed below said bottom wall, meansintroducing plastic at extrusion pressures into said holder, and afilter element having a disk sealed in said cavity above said bottomwall, said filter element having concentric rings integrally formed withsaid filter disk and upstanding therefrom to substantially fill saidcentral cavity, said filter element containing concentric circles ofclosely spaced upward extending bores for the outflow of filtered andconditioned material, said bores extending through said disk to theupper portions of said concentric rings. The area of the concentricrings is at least twice the cross-sectional area of the cavity and thevolume of the concentric rings above the filter disk within the cavityis at least 45 per cent the volume of the central cavity above thefilter disk.

Since the upstanding concentric rings substantially fill the centralcavity of the spinnerette head assembly, sand or marbles need not beused for this purpose. In addition, the concentric rings present a muchlarger area for filtering purposes with a given thickness for a flowpath so that, with a given pore size, a longer service life beforeclogging results. The concentric ring construction of the filter elementof this invention provides a stronger filter that more thoroughly fillsthe central'cavity than does the filter shown in my US. Pat. No.3,570,059.

BRIEF DESCRIPTION OF THE DRAWING FIG. 4; and

FIG. 6 is a section taken on line 6--6 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2,plastic at extrusion pressures, which may be several thousand p.s.i., isforced through a feed pipe 10 into a spinnerette head assembly 11. Pipe10 has a flange 12 formed at its end to which a corresponding flange 13of the cup-shaped holder 14 is fixed by the bolts 15. Holder 14 containsa large central cavity 16 below which is an end wall 17 containingpassages 18. The undersurface of wall 17 has a circular recess 19 formedtherein into which the passages 18 communicate. An extrusion disk 20,known as a spinnerette disk, contains the extrusion aperturesor orifices21 through which fibers are extruded. Spinnerette disk is fixed belowwall 17 over recess 19 by the bolts 22.

A screen 23 may be placed on end wall 17 to have the filter disk 24 offilter element 30 rest on it. A U- shaped seal 25 or the equivalent ofsoft metal such as aluminum prevents leakage of plastic past theperiphery of disk 24. Filter element has a plurality of concentricupstanding rings 26, 27, and 28 formed about a single circular element29. As may be seen in FIG. 3, concentric circles 31, 32, and 33 ofupward extending bores 34 are disposed about a central bore 35. Thebores 34 and the bore 35 extend through disk 24 to the upper portions ofthe upstanding rings 31, 32 and 33 and circular element 29,respectively.

The entire filter element 30 is integrally formed of sintered powderedmetal, preferably of stainless steel.

The concentric upstanding rings 26, 27, and 28 and the central element29 have the small clearances 37, 38., and 39 between them so that filterelement 30 fills or occupies at least 45 per cent of the total volume ofcavity 16 above disk 24. This is a great advantage in reducing thestagnation of material in head 11.

Any number of rings 26, 27, and 28 may be provided to fill the volume ofcavity 16 and present a large filter area to inflowing material. While acenter element 29 is shown, it may be omitted if desired. The structureof filter element 30 is easily fabricated and it is particularly strongso that it better resists the high pressures involved in syntheticpolymer fiber extrusion.

The second embodiment of this invention, which is shown in FIGS. 4-6,comprises a filter element 40 having a disk portion 41 and concentricrings 42 and 43 upstanding therefrom. Concentric circles 44 and 45 ofupward extending bores 46 extend through disk 41 into the rings 42 and43. A single central element 47 contains an upward bore 48. To provide aflow path of uniform length through the concentric upstanding rings tothe bores 46, scallops 50 are formed in the inner and outer surfaces ofthe rings 42 and 43. The scallops 50 are formed to each extendconcentrically about a bore 46. Ifa central element 47 is provided, itsouter surface should curve with the same radius as the scallops 50 aboutits bore 48.

While this invention has been shown and described in the best formsknown to me, it will nevertheless be understood that these are purelyexemplary and that modifications may be made without departing from thespirit of the invention.

Iclaim:

1. A filter element for use in 'a spinnerette head for the extrusion ofsynthetic polymer fibers, said spinnerette head having a holder withmeans securing and sealing said filter element therein, said holdercontain ing a large central cavity in front of said filter element, apipe introducing plastic at extrusion pressures into the large centralcavity of said holder, and a spinnerette disk containing extrusionapertures fixed to said holder below said filter element, said filterelement comprising, in combination, a filter disk secured and sealedwithin said holder by said means, and a plurality of upstanding,concentric rings extending from said filter disk, said disk and saidrings being integrally formed of porous material, said rings occupyingat least 45 per cent of the volume of the central cavity of said holder,said filter element presenting an area at least twice thecross-sectional area of said central cavity to inflowing syntheticpolymer material, said filter element containing upward extendingcircles of closely spaced outflow bores, said bores extending throughsaid disk to the upper portions of said concentric, upstanding rings.

2. The combination according to claim 1 with the addition of a centralelement of porous material extending upward from the center of saiddisk, said concentric rings extending about said central element, saidcentral element containing an outflow bore therein extending throughsaid 'disk to the upper portion of said central element.

3. The combination according to claim 1 with the addition of scallopsformed in the inner and outer surfaces of said rings about each boretherein, said scallops providing flow paths of substantially the samelength from the surfaces of said rings to the bores therein.

4. The combination according to claim 3 with the addition of a centralelement of porous material extending upward from the center of saiddisk, said concentric rings being disposed about said central element,said central element containing an outflow bore extending through saiddisk to the upper portion of said central element, said central elementhaving an outer surface with the same radius of curvature as saidscallops.

1. A filter element for use in a spinnerette head for the extrusion ofsynthetic polymer fibers, said spinnerette head having a holder withmeans securing and sealing said filter element therein, said holdercontaining a large central cavity in front of said filter element, apipe introducinG plastic at extrusion pressures into the large centralcavity of said holder, and a spinnerette disk containing extrusionapertures fixed to said holder below said filter element, said filterelement comprising, in combination, a filter disk secured and sealedwithin said holder by said means, and a plurality of upstanding,concentric rings extending from said filter disk, said disk and saidrings being integrally formed of porous material, said rings occupyingat least 45 per cent of the volume of the central cavity of said holder,said filter element presenting an area at least twice thecross-sectional area of said central cavity to inflowing syntheticpolymer material, said filter element containing upward extendingcircles of closely spaced outflow bores, said bores extending throughsaid disk to the upper portions of said concentric, upstanding rings. 2.The combination according to claim 1 with the addition of a centralelement of porous material extending upward from the center of saiddisk, said concentric rings extending about said central element, saidcentral element containing an outflow bore therein extending throughsaid disk to the upper portion of said central element.
 3. Thecombination according to claim 1 with the addition of scallops formed inthe inner and outer surfaces of said rings about each bore therein, saidscallops providing flow paths of substantially the same length from thesurfaces of said rings to the bores therein.
 4. The combinationaccording to claim 3 with the addition of a central element of porousmaterial extending upward from the center of said disk, said concentricrings being disposed about said central element, said central elementcontaining an outflow bore extending through said disk to the upperportion of said central element, said central element having an outersurface with the same radius of curvature as said scallops.